Mixer



June 29, 1937. c. E. UNDERWOOD MIXER Original Filed Nov. 26, 1934 l 3 We a 9 1 F/ 9 jwid 1 A fli d! 3 J A X -3 I H m i uw wmnwfl Mmm- M155 Uzzdarwaad Patented June 29, 1937 hdiihldz FATNT FEFE ll/EIXER Charles E. lllnderwmid, Bethlehem, Pa, assignor to Bethlehem Steel Company, a corporation of Pennsylvania (lriginal application November 26, 1934, Serial 20 Claims.

My present invention relates to mixing apparatus, and more especially to a mixer adapted for use in mixing a basic solution with crude tar or the like in the process of separating tar acids therefrom, and is a division of a co-pending application, filed jointly by me and Charles M. Ambler, Jr., November 26, 1934, entitled, Method of extracting tar acids from crude tar, Serial No. 754,718.

One of the objects of the invention relates to mixing material by passing it through a plurality of chambers in a tortuous path.

Another object of the invention relates to the manner of arranging the tubular connections between the chambers in such a manner that the material will be divided as it passes from chamber to chamber and will be thoroughly mixed by a vertical and lateral continuous flow as it passes through the mixer.

s, Other objects will appear hereinafter.

The above mentioned co-pending application discloses a method by which tar acids are separated in a simple expeditious manner from crude tar which is produced incidental to the manu- {33 facture of coke.

As stated in this application in accordance with the usual process of manufacturing coke, a quantity of tarry material results as a by-product. This tarry material, or crude tar as it will here- :y after be called, has a specific gravity of around 1.06 to 1.18 and ordinarily contains from 2 /2 to 6% of tar acids and up to about 10% of water. The tar acids which consist mainly of phenol and its homologues, such as the cresols and xylenols,

3.3 are valuable commercially but are quite difficult to isolate according to known procedures.

The practice heretofore has usually been todehydrate the crude tar either by evaporating off the water or centrifuging. After dehydrating, the

43 crude tar is distilled in a tar still and separated into two fractions, the fraction boiling below 250 0. being known as tar oil and the remainder simply as tar, or a tar residue, the tar acids, being substantially wholly contained in the tar oil, and

being present therein in a concentration of between 15 and This tar fraction is subjected to further treatment to separate the acids. Such treatment ordinarily consists in intermixing the tar oil with an aqueous caustic soda. solution of a concentration suflicient to convert the tar acids into pheolates, cresolates and the like. These compounds, which may be designated generally as phenolates, dissolve readily in the caustic solu- 55 tion and are subsequently separated from the tar Divided and November 7, rest, Serial No.

this application 48,628

oil by allowing the mixture to settle into an aqueous layer and an oil layer and then decanting. The aqueous solution so obtained is thereafter treated with an acid, usually sulphuric, to convert the dissolved compounds back to tar acids. 5 The tar acids, being insoluble, are thereafter separated from the resulting solution of sodium sulphate by gravity settling.

The dimculty with such a process is that it requires a dehydration and distillation of the 10 heavy tarry material which is difiicult and troublesome and which many coke plants are not equipped to accomplish. Hence the tar must often be sold without extracting the tar acids therefrom, to refineries especially equipped for 15 this work and these refineries must be equipped to carry out the relatively long and involved process outlined above.

It has been found by actual practice that if original tarry material is mixed directly with a 20 basic solution of caustic potash capable of convertin the tar acids into the corresponding phenolates, and thereafter separated from such to avoid emulsion difficulties, such separation can be effected, and the separated solution will con- 5 tain substantially all of the tar acids in the form of soluble phenolates. These compounds may thereafter be reconverted into tar acids by the addition of acid and separated.

A feature of considerable importance in carrying out the process relates to the manner of mixing the basic solution with the crude tar. The invention can be practiced in a general way by simply mixing a dilute basic solution with this material and thereafter promptly separating. However, the process may be performed in a far more expeditious manner by taking advantage of an apparently anomalous phenomenon that these inventors have discovered.

According to this newly discovered phenomenon, if a relatively concentrated basic solution be first added to the tar and intermixed therewith and then subsequently a quantity of water be added to the mixture, the resultant mixture may be expeditiously separated, for example, by centrifuging, by the addition of a much smaller quantity of liquid than would be necessary to condition the mass for the ultimate separating step if all of the liquid were added as a part of the original basic solution.

While an academic consideration of the problem might make it seem rather obvious to extract the tar acids directly from the tarry residue rather than from the separated tar oil, such is not the case. Tar oil is a material of relatively low viscosity as compared with the original tarry material from the coke plant and hence the fact that the tar oil can be treated with a basic solution and thereafter separated from the solution, in no way indicates that the original tarry material can be so treated in commercial quantities. This original tar, in contra-distinction to the tar oil, is a heavy, viscous material and when mixed with a basic solution with suflicient intimacy to insure reaction, tends to become emulsified therewith and thereafter is separable only with the greatest of diiilculty.

Having thus given a general description of the application of my invention I will now, in order to make the invention more clear, refer to the annexed sheet of drawing forming a part of this specification and in which like characters of reference refer to like parts.

Figure l is a vertical section of the mixer, and Fig. 2 is a transverse sectional view of the mixer taken on the line 22 of Fig. 1.

In the preferred practice of the invention the crude tar from the coke plant is first treated by the addition thereto of a solution of an alkali metal hydroxide, preferably caustic soda, containing approximately one pound of caustic soda for each two and one-half pounds of tar acids in the tar. The caustic solution is usually varied in strength between 10% by weight of caustic and 25% by weight of caustic according to the proportion of tar acids in the tar. tains around 2 tar acids, the solution used is usually of around 10% concentration whereas if the percent of tar acids in the tar is around 6% this caustic solution will be of around 25% concentration.

The caustic solution and the tar are passed into a mixer preferably of the tortuous path type, such as shown in Figs. 1 and 2, where they are intimately mixed. During the course of the mixing operation, and preferably toward the end thereof, a quantity of water is added and this tends to make the phases of the mixture separate readily. Ordinarily an amount of water about equal in volume to that of the original caustic solution is added and this amount is usually sufiicient to reduce the specific gravity of the aqueous phase far enough below the specific gravity of the tar phase to render subsidence separation possible. If not, more water may be added. In some instances however, a smaller quantity of water may be added so that the aqueous solution remains the heavier phase and is separated as such. The mixing step is of considerable importance in that the manner of its performance greatly affects the subsequent separation of the aqueous solution and unreacted tar;

As shown the mixer l, consists of an outer shell 2 within which is formed a stack of short cylindrical chambers 3, the adjacent chambers being separated by partition walls A. Tubular members 5 and 6 extending through these walls, permit the passage of the liquid from chamber to chamber throughout the stack; Alternate partition walls have similarly arranged tubular members projecting through them, while the tubular members through the remaining. walls are offset in relation thereto. Thus in one set of partition walls each wall has a relatively large di ameter tube 5 passing axially through the center thereof while in the remaining set of walls which alternate with these walls in their position in the stack, each wall is pierced by four smaller tubes 6, also extending in an axial direction but oifset If the tar confrom the larger tubes 5. Each of the tubes 5 and 6 extends not only into the chambers which it connects but nearly to the opposite walls of these chambers. The distance between each end of the tube and the corresponding wall is preferably such that the distance from the end of the tube to the adjacent wall is approximately equal to one fourth of the diameter of the tube itself. Furthermore, the cross-sectional area of the large tube 5 is substantially equal to the combined cross-sectional areas of the four smaller tubes 6.

It has been found most desirable to use about fifteen chambers in a mixer of this type although a greater or less number may be used, and to add the water at approximately the tenth chamber from the entrance end through an inlet pipe '5. As indicated in the drawing we prefer to enter the tar and caustic solution to the chamber through an inlet 8 at the bottom of the stack and have it flow upwardly in a tortuous path indicated by the arrow in Fig. l and finally discharged at the top as at 9 and conducted to a centrifuge, but this flow may be reversed if desired, and various modifications may be made in the mixer construction and the water may be added at other times than when the mixture passes through the tenth chamber. Also a dilute caustic solution may be added instead of Water.

If desired, instead of adding water during the mixing, the water may be added as a part of the original caustic solution. When the mixture is fed in this manner, however, the caustic solution originally used is much less concentrated, ordi' narily varying from 2 to 5% by weight of caustic soda in concentration, and a somewhat larger quantity of caustic in proportion to the tar acids should be present. Althoughit is possible to perform the operation in such a manner, when so performed it is much less economical and advantageous than when performed in the preferred manner by adding the water separately. More caustic must be used; the separation is more difiicult; the quantity of solution to be separated is greater; and more tar acid is lost because of failure to recover it from this larger quantity of caustic solution, in the case of the addition of all of the water as a part of the' original solution than in the case of dilution after mixing more concentrated caustic with the crude tar in accordance with our preferred procedure. Furthermore, in the performance of an operation in which all ofthe aqueous liquid is added at the beginning of the mixing operation, great difficulty is encountered in separating the residual tar from the phenolate solution in connection with treatments of crude tars of high acid content.

After the material emerges from the mixer it is promptly centrifuged and further treated as described in the above copending application.

For illustration I have described my apparatus for the purpose of mixing crude tar caustic soda and water together. I wish it understood that it could be used for mixing other materials in a similar manner.

In the mixing operation the material in an aqueous state is preferably fed under pressure into the lower chamber 3 of the mixer through the inlet opening 8 and flows upwardly through the four tubular members 6, which connect the lower two chambers. As it fiows out of the upper ends of these tubular members it engages the second partition wall which defiects it laterally and downwardly where it is again defiectedby the first partition wall into the lower end of the larger single central tubular connection for the second and third chambers where it flows upwardly and out of the upper end and engages the third partition wall where it is deflected outwardly and downwardly into the next set of four tubular connections for the third and fourth chambers. This tortuous flow just described is repeated a plurality of times until it reaches the opposite end of the mixer where it is ejected through the exit opening 9.

As indicated in Fig. 1 water or a caustic solution may be added through an inlet pipe I to one of the intermediate chambers during the mixing operation.

Although I have shown and described my invention in considerable detail, I do not wish to be limited to the exact and specific details shown and described, but may use such substitutions, modifications or equivalents thereof, as are embraced within the scope of my invention or as pointed out in the claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a mixing device of the class described comprising a series of chambers connected by tubular members each having their ends extending into a pair of chambers and located so as to form with the chambers a tortuous path, means at opposite ends of the tubular members for deflecting the material in opposite directions as it passes through each chamber, an inlet opening through which crude tar and a reagent are introduced into one end of the series of chambers and adapted to be mixed by its passage through the tortuous path, and an outlet at the opposite end of the series of chambers through which the material mixed is ejected.

2. In a mixing device of the class described comprising an outer shell, a plurality of spaced partition walls therein adapted to form a series of chambers connected together by tubular members each adapted to extend into a pair of chambers to form a tortuous path between each partition wall to mix material as it is advanced therethrough, an inlet adapted to receive crude tar and a reagent into one end of the tortuous path, means for deflecting the material in opposite directions as it passes through each chamber, and an outlet at the opposite end of the tortuous path in the mixing device through which the mixed material is ejected.

3. In a mixing device of the class described comprising a series of chambers connected by tubular members located so as to form with the chambers a tortuous path through the mixing device, deflecting means at the opposite ends of each tubular connection, an inlet adapted to receive crude tar and a reagent at one end of the tortuous path, an inlet for supplying water at an intermediate point in the tortuous path, and an outlet at the opposite end of the tortuous path through which the mixed material is adapted to be ejected.

4. In a device of the class described for mixing crude tar and a reagent, comprising a series of chambers, partition Walls between the chambers, tubular members supported at an intermediate point by the partition walls and extending therefrom for connecting a pair of chambers, the tubular members in one partition wall being in staggered relation and of smaller size than the tubular members in the adjacent walls and forming with the chambers a tortuous path through the mixing device, said partitions adapted to deflect material in opposite directions in each chamber, an inlet to the chambers at one end of the tortuous path through which crude tar and a reagent are introduced and adapted to be advanced by pressure through the tortuous path, and an outlet in the chamber at the opposite end of the tortuous path through which the mixture is ejected.

5. In a device of the class described for mixing crude tar and a reagent, comprising a series of chambers connected together by tubular members located so as to form with the chambers a tortuous path through the mixing device, an inlet in the chamber at one end of the tortuous path through which crude tar and a reagent are introduced and advanced through the tortuous path, partition walls between the chambers adapted to deflect the material in opposite directions in each chamber as it is advanced through the mixing device, an inlet in one of the intermediate chambers for adding water to the mixture as it is advanced through the mixing device, and an outlet in the chamber at the opposite end of the tortuous path through which the mixture is ejected.

6. In a mixing device of the class described comprising an outer shell, a plurality of spaced transversely extending partitions in the outer shell adapted to form thereby a series of chambers, central tubular members each connecting a pair of chambers together, a plurality of tubular members of smaller cross sectional area than the central tubular members for connecting pairs of chambers together in offset relation with the central tubular .connections, said partitions adapted to deflect the material in passing through each chamber in opposite directions, and an inlet and outlet opening at opposite ends of the series of chambers.

7. In a mixing device of the class described comprising a cylindrical shell, spaced transverse partitions in the shell adapted to form a plurality of chambers, a single tube centrally located extending through alternate partitions, tubes of smaller cross sectional area than the centrally located tubes extending through the partitions located intermediate the alternate partitions in staggered relation with the single central tubes, an inlet to the chamber at one end of the mixing device, and an outlet from the chamber at the opposite end of the cylindrical shell.

8. In a mixing device of the class described comprising a cylindrical shell, spaced transverse partitions in the shell adapted to form a plurality of chambers, a tube of relatively large cross sectional area extending centrally through alter nate partitions, a plurality of tubes of smaller cross sectional area than the centrally disposed tubes extending through the partitions located intermediate the alternate partitions in staggered relation with the central tubes, an inlet to the chamber at one end of the cylindrical shell for receiving material to be mixed, an inlet to one of the intermediate chambers through which additional material is fed, and an outlet from the cylindrical shell from which the mixed material is ejected.

9. In a mixing device of the class described comprising a stack of chambers connected alternately by a central tubular member of relatively large cross sectional area, a plurality of tubular members of smaller cross sectional area than the central tubular members connecting pairs of chambers in staggered relation with the central tubular members, an inlet to the chamber at one end of the stack of chambers for receiving material to be mixed, and an outlet from the chamberat the opposite end of the stack from which the material is ejected.

10. In a mixing device of the class described comprising a stack of chambers connected alterf nately by a central tubular member each extending into a pair of chambers, a plurality of tubular members extending into and connecting pairs of chambers arranged alternately and in staggered relation with the central tubular mem- -l bers, deflecting means at the opposite ends of the tubular connections, an inlet to the chamber atone end of the stack of chambers for receiving material to be mixed, an inlet to one of the intermediate chambers for feeding additional material to the mixing device, and an outlet from the chamber at the opposite end of the stack from which the mixed material is ejected.

11. In a mixing device of the class described 7 comprising a cylindrical'casing, transverse partitions in the cylindrical casing forming chambers therein, a tubular member disposed centrally each extending through and projecting from opposite sides of alternate partitions for connecting pairs of chambers together, a plurality of tubular members extending through and projecting from opposite sides of the partitions intermediate the alternate partitions connecting pairs of chambers in staggered relation with the central. tubular members, said partitions adapted to deflect the material in opposite directions as it passes through each chamber, an inlet through which material to be mixed is fed into one end of the cylindrical casing, an inlet in one of the intermediate chambers adapted to feed additional material to the mixture, and an outlet from the cylindrical casing from which the mixed material is ejected.

12. In a mixing device of the class described comprising a series of chambers connected by tubular members extending into a pair of chambers and so located as to form with the chambers a tortuous path for the material to advance it under pressure vertically and laterally during the mixing operation, means for deflecting the material in opposite directions in passing through each chamber, an inlet and outlet opening at opposite ends of the mixing device, and an inlet opening in one of the intermediate chambers through which additional material is fed to the mixture.

13. In a mixer of the class described comprising a cylindrical outer shell with a plurality of transverse partitions therein adapted to form a series of chambers within the shell, a tubular member in the central portion of the alternate transverse partitions, each adapted to connect pairs of chambers together, a plurality of tubular members of smaller cross sectional area than the central tubular members in each of the partitions intermediate the alternate transverse partitions and in staggered relation with the central tubular members for connecting pairs of chambers together, the tubular members being so located as to form with the chambers a tortuous path to advance the material under pressure during the mixing operation vertically and laterally, means for deflecting the material in opposite directions in each chamber, an inlet in the chamber at one end of the mixer through which crude tar and a reagent are adapted to be fed, an inlet in one of the intermediate chambers adapted for supplying water to the mixture, and an outletin the chamber at the opposite end of the mixer to that of the inlet through which the mixed material is ejected.

14. In a mixer of the class described comprising a cylindrical shell with a plurality of transverse partitions therein adapted to form a series of chambers, Within the shell, centrally aligned tubular members extending through alternate partitions for connecting a pair of the chambers together, a plurality of aligned'tubular members extending through a second set of alternately arranged partitions adapted to connect pairs of chambers in staggered relation with the centrally aligned tubular connections for giving the material under pressure a plurality of vertical and lateral movements as it is advanced through the mixer, means for deflecting the material in opposite directions as it passes through each chamber, an inlet opening at one end of the mixer adapted to receive crude tar and a reagent, an inlet opening adapted for supplying water to the mixture during the mixing operation, and an outlet at the opposite end of'the mixer to that of the inlet through which the mixed material is ejected. s

15. In a mixer of the class described comprising a cylindrical shell with a plurality of spaced transverse partitions therein adapted to form a series of chambers with the shell, the alternate partitions being each formed with a central tubular projection. having their ends extending nearly to the adjacent partitions, the partitions intermediate the alternate partitions being each provided with a plurality of tubular projections of smaller cross sectional area than the central tubular projections extending nearly to the alternate partitions on each side thereof and in staggered relation with the central tubular projections of the said alternate partitions, deflecting means at opposite ends of each tubular projection, an inlet and an outlet at opposite ends'of the mixer, and an inlet in one end of the intermediate chambers through which additional material is supplied to the mixture. a

16.- In a mixer of the class described comprising a cylindrical shell with a plurality of transverse partitions therein adapted to form a series of chambers within the shell, the alternate partitions each being formed with a tubular member having its ends spaced apart from the adjacent partitions a distance equal substantiallyto one fourth the diameter of the tubular member, partitions intermediate the said alternate partitions provided With a plurality of tubular members of smaller cross sectional area than the tubular member having their ends spaced apart from the alternately arranged partitions and in staggered relation with the tubular members in said partitions, a feeding inlet and an ejecting inlet at opposite ends of the mixer, and a feeding inlet in one of the intermediate chambers adapted for supplying additional material to the mixture. I 17. In a mixer of the class described comprising a cylindrical shell with a plurality of spaced transverse partitions therein adaptedto form a series of chambers within the shell, one set of alternately arranged partitions each being formed with a central tubular portion extending from opposite sides of the partition with its opposite ends spaced apart from the adjacent partitions, a second Set oi alternately arranged partitions each provided with a plurality of tubular portions having'their opposite ends in spaced relationto 'thefirst set of alternately arranged partitions and in staggered relation with the central tubular portions, the combined cross-sectional area of the tubular portions in each of the second set of alternately 5 arranged partitions being substantially equal to that of the cross-sectional area of each of the central tubular extending portions in the first set of partitions, a feeding inlet and an ejecting outlet at opposite ends of the mixer, and an additional feeding inlet in one of the intermediate chambers of the mixer.

18. In a mixer of the class described comprising a cylindrical shell with a plurality of spaced transverse partitions therein adapted to form a series of chambers Within the shell, one set of alternately arranged partitions each having a central tubular portion extending from opposite sides of each of the partitions with its ends spaced apart from the adjacent partitions a distance equal to substantially one fourth of its cross-sectional area, a second set of partitions alternately arranged between the first set each provided with a plurality of tubular portions of smaller cross sectional area than the first set having their ends spaced apart from the first set of alternately arranged partitions a distance equal substantially to one fourth of their cross-sectional area, a feeding inlet and an ejecting outlet at opposite ends of the mixer, and an additional feeding inlet in one of the intermediate chambers of the mixer.

19. In a mixer of the class described comprising a cylindrical shell having a plurality of spaced transverse partitions therein adapted to form a series of chambers Within the shell, one set of alternately arranged partitions each having a plurality of tubular portions extending therefrom in opposite directions, each of said tubular portions of one partition being in vertical alignment with one of the tubular projections in the other alternately arranged partitions, a second set of alternately arranged partitions each having a central tubular extension on opposite sides of the partitions having a cross-sectional area substantially equal to the combined crosssectional areas of the plurality of tubular extensions in the first set of partitions and in staggered relation therewith, the ends of the tubular extensions being spaced apart from the adjacent partitions a distance substantially equal to one fourth their cross-sectional areas, a feeding inlet and an ejecting outlet at opposite ends of the mixer, and an additional feeding inlet in one of the intermediate chambers of the mixer.

20. In a mixer of the class described adapted for mixing crude tar and a reagent or the like comprising a cylindrical shell having a plurality of spaced transverse partitions therein thereby forming a series of chambers Within the shell, a single central tubular member extending from both sides of each of the alternate partitions, a plurality of tubular members extending from both sides of another alternately arranged set of partitions and in offset relation with the single central tubular extensions, means at opposite ends of the tubular members for deflecting the material in opposite directions as it passes through each chamber, said tubular members with the partitions adapted to form a tortuous path in each chamber for the crude tar and a reagent as it is advanced through the mixer, a feeding inlet at one end of the mixer for introducing the crude tar and the reagent into one end of the mixer, an inlet for introducing Water to one of the intermediate chambers during the mixing operation, and an outlet for ejecting the mixed material from the mixer.

CHARLES E. UNDERWOOD, 

